Teams will be split into four groups of three, with the group winners then contesting the UEFA Nations League Finals (semi-finals, third-place match and final) in June 2019 to become the UEFA Nations League winners. One host country will be appointed in December 2018 from among the finalist teams.

The four sides that finish bottom of their groups will be relegated to League B for the 2020 edition.

The top four-ranked League A teams that do not qualify for UEFA EURO 2020 will enter play-offs in March 2020, with one finals place on offer.

Teams will be split into four groups of three. The four group winners are promoted to League A, with the four sides that finish bottom relegated to League C for the next competition, to be played in 2020.

The top four-ranked League B teams that do not qualify for UEFA EURO 2020 will enter play-offs in March 2020, with one finals place on offer.

Teams will be split into one group of three and three groups of four. The four group winners are promoted to League B, with the four sides that finish bottom relegated to League D for the 2020 edition.

The top four-ranked League C teams that do not qualify for UEFA EURO 2020 will enter play-offs in March 2020, with one finals place on offer.

Teams will be split into four groups of four, with the four group winners promoted to League C for the 2020 edition.

The top four-ranked League D teams that do not qualify for UEFA EURO 2020 will enter play-offs in March 2020, with one finals place on offer.

The 55 participating teams were split according to their position in the UEFA National Team Coefficient Rankings following the end of the European Qualifiers for the 2018 FIFA World Cup (as per 11 October 2017; play-off results will not be included).